Burn-in systems have been used to increase the reliability of Integrated Circuit (IC) products. A fresh IC from a fabrication process may function properly initially but fail after a short period of operation, due to, for example, a metal wire within the IC that is too irregular or too thin to carry changing electrical current without significant damaging effects such as electron migration or localized heating. A burn-in process subjects the semiconductor devices, such as IC chips, to age-accelerating stress to weed out the IC chips that would fail early. It could be very expensive if such early failures occurred during the actual use of an IC in a system, in terms of user satisfaction and the cost to replace the failed IC in the system. It's much more cost-effective to catch those early failures before the ICs are delivered to customers and assembled into systems. A burn-in process can drive such IC chips into failure, preventing them from being assembled into the system to cause early failure in delivered products. Further, a prolonged burn-in test of samples of a batch of ICs can be used to estimate the life expectancy of the ICs and the reliability of the ICs.
A burn-in process may subject the semiconductor devices to extreme operating conditions, such as heat, high operating voltages, high humidity, etc., in a burn-in chamber (e.g., a burn-in oven). Circuit boards (burn-in boards) are used to hold the semiconductor devices in the burn-in chamber; and power and clock signals are provided to the semiconductor devices via the burn-in boards. Wires are used to supply power and clock signals to the burn-in boards. The power and clock signals may be provided by a driver board that is located outside the burn-in chamber.
In a static burn-in oven, the input pins of the ICs are not given any input stimuli. In such a static burn-in system, a large portion of the circuit nodes of a complex IC are not toggle due to the constant signals for the input pins.
In a dynamic burn-in oven, the input pins of the ICs are provided with varying input. When carefully designed, the changing input stimuli provided to the input pins of the ICs can fully exercise at least the majority of the circuit nodes of a complex IC. In some ICs, such as Complementary Metal Oxide Semiconductor (CMOS) based ICs, the circuit draws more current and consumes more power when the states of the circuit nodes are toggled. Thus, a dynamic burn-in oven can burn in the ICs more effectively than a static burn-in oven. Currently, it is difficult to achieve real dynamic life testing for most of mixed-signal and RF ICs which have analog and/or RF parts.
A dynamic burn-in system includes an input generator, which may be located outside of the burn-in oven, or inside the burn-in oven. For example, U.S. Pat. No. 5,798,653, entitled “Burn-in System for Reliable Integrated Circuit Manufacturing”, describes a dynamic burn-in system in which a burn-in controller IC is used inside the burn-in oven to generate digital stimuli for the input pins of the ICs that are subject to the burn-in process.
An Arbitrary Waveform Generator (AWG) is often used as the input signal generator for a dynamic burn-in process. Because AWGs synthesize the waveforms using digital signal processing techniques, their maximum frequency is usually limited to no more than 20 Megahertz.